thiL encodes thiamine-monophosphate kinase (EC 2.7.4.16), which catalyzes the ATP-dependent phosphorylation of thiamine monophosphate (TMP) to form thiamine pyrophosphate (TPP), the biologically active cofactor form of vitamin B1. ThiL is a homodimeric enzyme belonging to the PurM-like ATP-binding superfamily with a bilobal fold (N-terminal and C-terminal PurM-like domains). Structural studies on homologs from Aquifex aeolicus and Acinetobacter baumannii demonstrate that ThiL uses a direct in-line transfer of the gamma-phosphate of ATP to TMP, rather than a phosphorylated enzyme intermediate. The active site requires multiple magnesium ions and sits at the dimer interface. In M. jannaschii, thiamine biosynthesis uses a chimeric pathway with a eukaryote-like Thi4 (iron-dependent thiazole synthase) and bacterium-like ThiC (HMP-P synthase), regulated by the transcriptional repressor ThiR rather than a riboswitch. ThiL catalyzes the terminal step of this pathway, converting TMP to the active cofactor TPP. All current annotations for Q60337 are based on homology; no direct experimental characterization of this specific M. jannaschii protein exists.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0000287
magnesium ion binding
|
IEA
GO_REF:0000104 |
ACCEPT |
Summary: IEA annotation for magnesium ion binding based on UniRule transfer (HAMAP MF_02128). Crystal structures of ThiL homologs show multiple magnesium ions coordinating the phosphate groups of ATP and TMP in the active site. Sullivan et al. (2019) demonstrated that the transferred phosphate groups specifically require magnesium ions, while other metal positions in the active site show more plasticity.
Reason: Magnesium binding is well supported by structural studies of ThiL homologs. Crystal structures from both A. aeolicus and A. baumannii confirm multiple Mg2+ ions in the active site. The M. jannaschii protein conserves all HAMAP-predicted magnesium binding residues. This is a core mechanistic feature of the enzyme.
Supporting Evidence:
PMID:30867460
a distinct variability of metal content of the active site
PMID:18311927
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1.
|
|
GO:0005524
ATP binding
|
IEA
GO_REF:0000104 |
ACCEPT |
Summary: IEA annotation for ATP binding based on UniRule transfer (HAMAP MF_02128). ThiL is a member of the PurM-like ATP-binding superfamily and ATP is one of the two substrates of the enzyme. Crystal structures confirm a deeply buried ATP binding pocket at the dimer interface.
Reason: ATP is a direct substrate of ThiL. The ATP binding site is formed by conserved residues in the interdomain cleft of the bilobal PurM-like fold. Structural studies on homologs confirm ATP binding in this pocket. The M. jannaschii protein conserves the key ATP-binding residues predicted by HAMAP.
Supporting Evidence:
PMID:18311927
ThiL is a member of a small ATP binding superfamily that also includes the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase maturation protein, HypE, and selenophosphate synthase, SelD.
PMID:30867460
the ATP-dependent phosphorylation of thiamine monophosphate (TMP) to thiamine pyrophosphate
|
|
GO:0009030
thiamine-phosphate kinase activity
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: IEA annotation for the core molecular function of ThiL, based on combined automated annotation methods including InterPro IPR006283, RHEA:15913, and EC:2.7.4.16. This is the defining enzymatic activity of the ThiL family: ATP-dependent phosphorylation of TMP to form TPP.
Reason: This is the core molecular function of ThiL. The M. jannaschii protein matches all family-defining signatures (IPR006283, TIGR01379, PTHR30270, CDD cd02194) and conserves the catalytic residues. Structural studies on homologs demonstrate this activity proceeds via direct in-line transfer of the gamma-phosphate of ATP to TMP.
Supporting Evidence:
PMID:18311927
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1.
PMID:30867460
Thiamine monophosphate kinase (ThiL) catalyzes the last step of thiamine pyrophosphate (TPP) synthesis
file:METJA/thiL/thiL-deep-research-bioreason-sft.md
A cytosolic enzyme that phosphorylates thiamine monophosphate using ATP to produce thiamine pyrophosphate, the active coenzyme form required for central carbon metabolism.
|
|
GO:0009228
thiamine biosynthetic process
|
IEA
GO_REF:0000002 |
KEEP AS NON CORE |
Summary: IEA annotation for involvement in thiamine biosynthetic process based on InterPro2GO mapping from IPR006283 (Thiamine-monophosphate kinase-like). ThiL catalyzes the terminal step of thiamine diphosphate biosynthesis, converting TMP to TPP. While ThiL is correctly part of the thiamine biosynthetic pathway, the more specific term GO:0009229 (thiamine diphosphate biosynthetic process) better captures its role.
Reason: ThiL is part of the overall thiamine biosynthetic pathway, so this annotation is not incorrect. However, it is less specific than GO:0009229 (thiamine diphosphate biosynthetic process), which directly describes the step ThiL catalyzes. The more specific term is already annotated. This broader term is retained as non-core since it provides useful pathway context via InterPro2GO but does not capture the precise biological role.
Supporting Evidence:
PMID:18311927
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1.
|
|
GO:0009229
thiamine diphosphate biosynthetic process
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: IEA annotation for involvement in the thiamine diphosphate biosynthetic process based on combined automated methods (UniRule, UniPathway UPA00060). ThiL directly catalyzes the conversion of TMP to TPP (thiamine diphosphate), which is the sole step of this sub-pathway.
Reason: This is the most specific and accurate biological process annotation for ThiL. The enzyme catalyzes the single step from TMP to TPP, which is precisely the thiamine diphosphate biosynthetic process. UniPathway UPA00060 step UER00142 confirms this is a one-step pathway.
Supporting Evidence:
PMID:30867460
Thiamine monophosphate kinase (ThiL) catalyzes the last step of thiamine pyrophosphate (TPP) synthesis, the ATP-dependent phosphorylation of thiamine monophosphate (TMP) to thiamine pyrophosphate.
PMID:18311927
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1.
|
|
GO:0005737
cytoplasm
|
IEA
GO_REF:0000002 |
NEW |
Summary: NEW annotation. ThiL is a soluble cytoplasmic enzyme with no transmembrane domains or signal peptides. The protein lacks any predicted export signals and the PurM-like bilobal fold is characteristic of soluble cytoplasmic enzymes. The BioReason SFT analysis also inferred cytoplasmic localization based on domain architecture.
Reason: ThiL is a soluble enzyme that acts on cytoplasmic substrates (ATP and TMP). The protein has no transmembrane domains, signal peptides, or other localization signals. Cytoplasmic localization is consistent with its enzymatic role in the thiamine biosynthetic pathway, where substrates and products are cytoplasmic metabolites. Although no direct experimental localization data exists for this archaeal protein, the inference is strong based on protein architecture and pathway context.
Supporting Evidence:
file:METJA/thiL/thiL-deep-research-bioreason-sft.md
the architecture lacks transmembrane segments or export signals and matches a soluble PurM-like bilobal enzyme, the most plausible cellular location is the cytosol
|
Q: Has ThiL from M. jannaschii been directly assayed for thiamine-phosphate kinase activity, and does the hyperthermophilic enzyme show any unusual kinetic or stability properties compared to mesophilic homologs?
Q: What is the physiological source of TMP in M. jannaschii -- does it use the canonical ThiE (thiamine phosphate synthase) or the bifunctional ThiDN?
Experiment: Express and purify recombinant M. jannaschii ThiL (Q60337) and perform in vitro kinase assays at thermophilic temperatures (65-85 C) to confirm thiamine-phosphate kinase activity and determine kinetic parameters. Compare with mesophilic ThiL enzymes to assess thermoadaptation.
Hypothesis: M. jannaschii ThiL will show optimal activity at hyperthermophilic temperatures (around 80 C) with kinetic parameters comparable to characterized ThiL enzymes from mesophilic organisms.
Experiment: Determine the crystal structure of M. jannaschii ThiL to compare the active site architecture with the known structures from A. aeolicus and A. baumannii, particularly examining metal coordination geometry at the higher physiological temperature of this organism.
Hypothesis: The M. jannaschii ThiL structure will reveal conserved active-site geometry with potential thermostabilizing features (e.g., additional salt bridges, compact hydrophobic core) compared to mesophilic homologs.
I begin with the InterPro architecture. The sequence is dominated by multiple overlapping signatures of the thiamine-monophosphate kinase-like family: IPR006283 (Thiamine-monophosphate kinase-like, family) spans residues 1β318, 1β305, 1β303, and 2β299, and is also captured as IPR006283 [3β303]. Embedded within this family scaffold are two PurM-like structural modules: an N-terminal PurM-like domain (IPR016188, residues 27β138) nested inside the PurM-like N-terminal domain superfamily (IPR036921, residues 1β142 and 2β139), followed by a C-terminal PurM-like domain superfamily (IPR036676, residues 145β317 and 146β303). This arrangementβan N-lobe and a C-lobe that together form a bilobal PurM-like foldβcreates a cleft that binds a nucleotide and a small-molecule acceptor. In thiamine-phosphate kinases, this bilobal architecture positions ATP in the interdomain cleft while a basic pocket recognizes the thiamine monophosphate (TMP) phosphate and pyrimidine, enabling in-line transfer of the Ξ³-phosphate from ATP to TMP. The repeated, nearly coterminous family signatures (residues ~1β317) indicate a single compact enzyme without accessory domains, consistent with a soluble, single-subunit kinase.
This domain architecture causally supports two molecular functions. First, the interdomain cleft and conserved P-loop-like/lysine-rich features typical of this fold create a canonical nucleotide-binding site, accounting for GO:0005524 ATP binding. Second, the family-defining chemistry of the thiamine-monophosphate kinase-like scaffold specifies GO:0004789 thiamine-phosphate kinase activity: the enzyme transfers a phosphate from ATP to TMP to generate thiamine pyrophosphate (TPP). The same active-site geometry can accommodate the closely related deaza analog, thus enabling activity toward 4-amino-5-hydroxymethyl-2-methylpyrimidin-4(3H)-one monophosphate (HOMO), i.e., a deazapurine monophosphate kinase reaction.
The catalytic output, TPP, is the active coenzyme form of thiamine diphosphate, a central cofactor for central carbon metabolism. Therefore, the enzymeβs activity directly drives GO:0009228 thiamine biosynthetic process by converting the monophosphate intermediate to the diphosphate coenzyme state. Because the architecture lacks transmembrane segments or export signals and matches a soluble PurM-like bilobal enzyme, the most plausible cellular location is the cytosol, aligning with GO:0005737 cytoplasm, where nucleotide and thiamine-pathway intermediates are abundant.
Mechanistically, the N- and C-terminal PurM-like lobes close around ATP and TMP to form a catalytically competent pocket. A conserved lysine and acidic residue network stabilizes the transition state and orients the phosphate groups for direct in-line transfer, yielding TPP and ADP. The same pocket tolerates the deaza analog HOMO, explaining the observed substrate flexibility. In the cellular context, this enzyme likely operates within a thiamine-biosynthesis metabolon: transient associations with thiamine biosynthesis protein (thiC) would channel upstream intermediates toward TMP, while adenylate kinase (adk) would buffer ATP/ADP ratios to sustain high-flux phosphoryl transfer. The proximity of purine-pathway enzymes such as GTP cyclohydrolase II (ribA) and phosphoribosylformylglycinamidine cyclo-ligase (purM) suggests a broader nucleotide-cofactor hub, where purine and thiamine biosynthesis co-localize to balance nucleotide pools and cofactor supply. Riboflavin synthase beta chain (ribH) indicates a possible cofactor biogenesis cluster coordinating multiple vitamin pathways. The proliferating-cell nucleolar antigen FMU/NOL1/NOP2 family protein implies a link to pyrimidine/folate-related metabolism, potentially stabilizing nucleotide pools that support cofactor synthesis. The conserved and hypothetical proteins likely act as adaptors or scaffolds that stabilize these transient assemblies, enhancing substrate channeling and protecting reactive intermediates. Altogether, the domain architecture dictates ATP-dependent phosphorylation of TMP (and HOMO) in the cytoplasm, feeding TPP production and integrating with adjacent vitamin and nucleotide metabolic nodes.
## Functional Summary
A cytosolic enzyme that phosphorylates thiamine monophosphate using ATP to produce thiamine pyrophosphate, the active coenzyme form required for central carbon metabolism. Its bilobal active site binds ATP and the thiamine phosphate acceptor to drive in-line phosphate transfer, and the same pocket can accept the deaza analog of the substrate, enabling phosphorylation of a deazapurine monophosphate. The enzyme likely operates within a metabolon that couples thiamine pathway intermediates to ATP supply and coordinates with neighboring vitamin and nucleotide biosynthetic enzymes to sustain cofactor production.
## UniProt Summary
Catalyzes the phosphorylation of thiamine-monophosphate (TMP) to thiamine-pyrophosphate (TPP). Also catalyzes the phosphorylation of 4-amino-5-hydroxymethyl-2-methylpyrimidin-4(3H)-one monophosphate (HOMO).
## InterPro Domains
- IPR006283: Thiamine-monophosphate kinase-like (family) [1-318]
- IPR006283: Thiamine-monophosphate kinase-like (family) [1-305]
- IPR006283: Thiamine-monophosphate kinase-like (family) [1-303]
- IPR036921: PurM-like, N-terminal domain superfamily (homologous_superfamily) [1-142]
- IPR006283: Thiamine-monophosphate kinase-like (family) [2-299]
- IPR036921: PurM-like, N-terminal domain superfamily (homologous_superfamily) [2-139]
- IPR006283: Thiamine-monophosphate kinase-like (family) [3-303]
- IPR016188: PurM-like, N-terminal domain (domain) [27-138]
- IPR036676: PurM-like, C-terminal domain superfamily (homologous_superfamily) [145-317]
- IPR036676: PurM-like, C-terminal domain superfamily (homologous_superfamily) [146-303]
## GO Term Predictions
### Molecular Function
### Biological Process
### Cellular Component
Gene: thiL (MJ0028)
Organism: Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440)
UniProt: Q60337
EC: 2.7.4.16
thiL encodes thiamine-monophosphate kinase (TMP kinase), which catalyzes the final step of thiamine pyrophosphate (TPP) biosynthesis: the ATP-dependent phosphorylation of thiamine monophosphate (TMP) to form thiamine pyrophosphate (TPP), the biologically active form of vitamin B1.
The gene was originally identified as MJ0028 in the M. jannaschii genome sequencing project [PMID:8688087, "Complete genome sequence of the methanogenic archaeon, Methanococcus jannaschii"]. The thiL gene name and function were assigned by homology to the E. coli thiL locus, which was first characterized by Imamura and Nakayama (1982) [PMID:6284709, "the latter lacks thiamine monophosphate kinase activity"].
Structural studies of ThiL from Aquifex aeolicus by McCulloch et al. (2008) established the mechanism of the enzyme [PMID:18311927, "The results suggest that AaThiL utilizes a direct, inline transfer of the gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme intermediate"]. This distinguishes ThiL from other members of the PurM-like ATP-binding superfamily (PurM, PurL, HypE, SelD), which are believed to utilize phosphorylated intermediates during catalysis.
The Sullivan et al. (2019) crystal structures of A. baumannii ThiL in complex with substrates and products provided further support for this mechanism at high resolution [PMID:30867460, "The structures further support a previously proposed in-line attack reaction mechanism and show a distinct variability of metal content of the active site"]. Their structures show that the alpha-phosphate of TMP is positioned for in-line attack on the gamma-phosphate of ATP, and that even the product complex closely matches the substrate complex conformationally -- "the transferred phosphate group, the gamma-phosphate in AMPPNP and the beta-phosphate in TPP, barely changes position. The distance between the phosphorous atoms is only 1.0 A."
ThiL belongs to the PurM-like ATP-binding superfamily with a bilobal fold consisting of an N-terminal domain (PurM-like N-terminal fold, IPR016188/IPR036921) and a C-terminal domain (PurM-like C-terminal fold, IPR036676). The active site resides in the cleft between these two domains and also spans the dimer interface [PMID:30867460, "The active site is located in the dimer interface. ATP/ADP is deeply buried in pocket generated at the interface between molecule A and B"].
ThiL functions as a homodimer. The enzyme binds multiple magnesium ions in the active site to coordinate the phosphate groups of ATP and TMP [PMID:30867460, "the active site can accommodate a variety of metals, and that the metal content is in part influenced by the crystallization condition"]. However, magnesium appears to be the physiologically relevant metal, particularly for the transferred phosphate groups.
The thiamine biosynthetic pathway in archaea is a chimera of eukaryote- and bacterium-type pathways [PMID:28115546, "In archaea, thiamine biosynthesis is an apparent chimera of eukaryote- and bacterium-type pathways that is not well defined at the level of enzymatic steps or regulatory mechanisms"]. M. jannaschii uses a eukaryote-like Thi4 for thiazole synthesis (which uses iron-dependent sulfide transfer rather than the suicide mechanism of yeast Thi4) [PMID:26928142, "the Thi4 ortholog from Methanococcus jannaschii uses exogenous sulfide and is catalytic"], and a bacterium-like ThiC for pyrimidine synthesis. In contrast, regulation of thiamine biosynthesis in archaea occurs via a transcriptional repressor ThiR rather than the riboswitch mechanism common in bacteria [PMID:28115546, "thiamine biosynthesis in archaea is regulated by a transcriptional repressor, ThiR, and not by a riboswitch"].
Comparative genomics analysis by Rodionov et al. (2002) predicted that archaea, eubacteria, and eukaryota have different pathways for HMP and thiazole biosynthesis [PMID:12376536, "eubacteria, archaea, and eukaryota have different pathways for the HMP and hydroxyethylthiazole biosynthesis"].
ThiL is essential in bacteria (demonstrated in A. baumannii by transposon mutagenesis) and has no human homolog, making it an attractive antimicrobial target [PMID:30867460, "Humans lack ThiL, potentially making it an attractive antimicrobial therapeutic target for pathogens"]. Recent computational studies have explored ThiL as a drug target in Leptospira species PMID:41662777.
Source: thiL-deep-research-bioreason-sft.md
The BioReason SFT functional summary correctly identifies the core function of thiL:
A cytosolic enzyme that phosphorylates thiamine monophosphate using ATP to produce thiamine pyrophosphate, the active coenzyme form required for central carbon metabolism.
This is accurate and aligns well with published literature (PMID:18311927, PMID:30867460). The summary also correctly notes the in-line phosphate transfer mechanism:
Its bilobal active site binds ATP and the thiamine phosphate acceptor to drive in-line phosphate transfer
This is supported by McCulloch et al. (2008): "The results suggest that AaThiL utilizes a direct, inline transfer of the gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme intermediate."
However, there are several issues that reduce the correctness score:
Unsupported deazapurine claim: The functional summary states that "the same pocket can accept the deaza analog of the substrate, enabling phosphorylation of a deazapurine monophosphate." While the UniProt entry does mention activity toward 4-amino-5-hydroxymethyl-2-methylpyrimidin-4(3H)-one monophosphate (HOMO), the functional summary over-emphasizes this as a core feature. It is a secondary activity mentioned in HAMAP annotations and not central to the biological role.
Speculative metabolon claims: The functional summary asserts "The enzyme likely operates within a metabolon that couples thiamine pathway intermediates to ATP supply and coordinates with neighboring vitamin and nucleotide biosynthetic enzymes to sustain cofactor production." There is no published evidence for a ThiL-containing metabolon. This is an extrapolation from genomic neighborhood without experimental support.
GO term GO:0004789 confusion: The thinking trace refers to "GO:0004789 thiamine-phosphate kinase activity" but GO:0004789 is actually "thiamine-phosphate diphosphorylase activity" (ThiE), not ThiL. The correct term for ThiL is GO:0009030 (thiamine-phosphate kinase activity). This is a factual error in the reasoning trace.
Missing cytoplasm localization nuance: The summary claims "GO:0005737 cytoplasm" as a localization, which is reasonable for a soluble enzyme without transmembrane domains. However, this is stated with higher confidence than warranted since no direct experimental localization data exists for this archaeal protein.
For completeness, the summary captures the core enzymology but misses several aspects:
The InterPro2GO annotation from GO_REF:0000002 maps IPR006283 (Thiamine-monophosphate kinase-like) to GO:0009228 (thiamine biosynthetic process). This is a correct but broad annotation.
The BioReason SFT summary is more informative than the InterPro2GO mapping in the following ways:
- It correctly identifies the specific enzymatic activity (TMP phosphorylation) beyond just pathway membership.
- It describes the in-line phosphoryl transfer mechanism.
- It mentions the bilobal PurM-like fold architecture.
However, BioReason also makes the same kind of errors that InterPro2GO avoids by being conservative:
- BioReason introduces speculative claims about metabolons and substrate channeling that have no evidence.
- BioReason incorrectly references GO:0004789 (ThiE activity) instead of GO:0009030 (ThiL activity) in the thinking trace.
- InterPro2GO sticks to what the domain architecture supports, while BioReason extrapolates beyond the evidence.
Overall, the BioReason functional summary provides genuine additional insight beyond InterPro2GO (mechanism description, structural context), but introduces errors and speculation that InterPro2GO avoids by design. The core identification of function is not merely a recapitulation of InterPro2GO -- it adds mechanistic detail -- but the added content has a mixed quality level.
The thinking trace is verbose and largely sound in its domain architecture analysis. The initial analysis of InterPro domains is accurate. However:
id: Q60337
gene_symbol: thiL
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:243232
label: Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM
10045 / NBRC 100440)
description: >-
thiL encodes thiamine-monophosphate kinase (EC 2.7.4.16), which catalyzes the
ATP-dependent phosphorylation of thiamine monophosphate (TMP) to form thiamine
pyrophosphate (TPP), the biologically active cofactor form of vitamin B1. ThiL
is a homodimeric enzyme belonging to the PurM-like ATP-binding superfamily with a
bilobal fold (N-terminal and C-terminal PurM-like domains). Structural studies on
homologs from Aquifex aeolicus and Acinetobacter baumannii demonstrate that ThiL
uses a direct in-line transfer of the gamma-phosphate of ATP to TMP, rather than
a phosphorylated enzyme intermediate. The active site requires multiple magnesium
ions and sits at the dimer interface. In M. jannaschii, thiamine biosynthesis uses
a chimeric pathway with a eukaryote-like Thi4 (iron-dependent thiazole synthase)
and bacterium-like ThiC (HMP-P synthase), regulated by the transcriptional
repressor ThiR rather than a riboswitch. ThiL catalyzes the terminal step of this
pathway, converting TMP to the active cofactor TPP. All current annotations for
Q60337 are based on homology; no direct experimental characterization of this
specific M. jannaschii protein exists.
existing_annotations:
- term:
id: GO:0000287
label: magnesium ion binding
evidence_type: IEA
original_reference_id: GO_REF:0000104
review:
summary: >-
IEA annotation for magnesium ion binding based on UniRule transfer (HAMAP
MF_02128). Crystal structures of ThiL homologs show multiple magnesium ions
coordinating the phosphate groups of ATP and TMP in the active site.
Sullivan et al. (2019) demonstrated that the transferred phosphate groups
specifically require magnesium ions, while other metal positions in the active
site show more plasticity.
action: ACCEPT
reason: >-
Magnesium binding is well supported by structural studies of ThiL homologs.
Crystal structures from both A. aeolicus and A. baumannii confirm multiple
Mg2+ ions in the active site. The M. jannaschii protein conserves all
HAMAP-predicted magnesium binding residues. This is a core mechanistic
feature of the enzyme.
supported_by:
- reference_id: PMID:30867460
supporting_text: >-
a distinct variability of metal content of the active site
- reference_id: PMID:18311927
supporting_text: >-
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent
phosphorylation of thiamin monophosphate (TMP) to form thiamin
pyrophosphate (TPP), the active form of vitamin B 1.
- term:
id: GO:0005524
label: ATP binding
evidence_type: IEA
original_reference_id: GO_REF:0000104
review:
summary: >-
IEA annotation for ATP binding based on UniRule transfer (HAMAP MF_02128).
ThiL is a member of the PurM-like ATP-binding superfamily and ATP is one of
the two substrates of the enzyme. Crystal structures confirm a deeply buried
ATP binding pocket at the dimer interface.
action: ACCEPT
reason: >-
ATP is a direct substrate of ThiL. The ATP binding site is formed by
conserved residues in the interdomain cleft of the bilobal PurM-like fold.
Structural studies on homologs confirm ATP binding in this pocket. The
M. jannaschii protein conserves the key ATP-binding residues predicted
by HAMAP.
supported_by:
- reference_id: PMID:18311927
supporting_text: >-
ThiL is a member of a small ATP binding superfamily that also includes
the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase
maturation protein, HypE, and selenophosphate synthase, SelD.
- reference_id: PMID:30867460
supporting_text: >-
the ATP-dependent phosphorylation of thiamine
monophosphate (TMP) to thiamine pyrophosphate
- term:
id: GO:0009030
label: thiamine-phosphate kinase activity
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
IEA annotation for the core molecular function of ThiL, based on combined
automated annotation methods including InterPro IPR006283, RHEA:15913, and
EC:2.7.4.16. This is the defining enzymatic activity of the ThiL family:
ATP-dependent phosphorylation of TMP to form TPP.
action: ACCEPT
reason: >-
This is the core molecular function of ThiL. The M. jannaschii protein matches
all family-defining signatures (IPR006283, TIGR01379, PTHR30270, CDD cd02194)
and conserves the catalytic residues. Structural studies on homologs demonstrate
this activity proceeds via direct in-line transfer of the gamma-phosphate of
ATP to TMP.
supported_by:
- reference_id: PMID:18311927
supporting_text: >-
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent
phosphorylation of thiamin monophosphate (TMP) to form thiamin
pyrophosphate (TPP), the active form of vitamin B 1.
- reference_id: PMID:30867460
supporting_text: >-
Thiamine monophosphate kinase (ThiL) catalyzes the last step of thiamine
pyrophosphate (TPP) synthesis
- reference_id: file:METJA/thiL/thiL-deep-research-bioreason-sft.md
supporting_text: >-
A cytosolic enzyme that phosphorylates thiamine monophosphate using ATP
to produce thiamine pyrophosphate, the active coenzyme form required
for central carbon metabolism.
- term:
id: GO:0009228
label: thiamine biosynthetic process
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: >-
IEA annotation for involvement in thiamine biosynthetic process based on
InterPro2GO mapping from IPR006283 (Thiamine-monophosphate kinase-like). ThiL
catalyzes the terminal step of thiamine diphosphate biosynthesis, converting
TMP to TPP. While ThiL is correctly part of the thiamine biosynthetic pathway,
the more specific term GO:0009229 (thiamine diphosphate biosynthetic process)
better captures its role.
action: KEEP_AS_NON_CORE
reason: >-
ThiL is part of the overall thiamine biosynthetic pathway, so this annotation
is not incorrect. However, it is less specific than GO:0009229 (thiamine
diphosphate biosynthetic process), which directly describes the step ThiL
catalyzes. The more specific term is already annotated. This broader term is
retained as non-core since it provides useful pathway context via InterPro2GO
but does not capture the precise biological role.
supported_by:
- reference_id: PMID:18311927
supporting_text: >-
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent
phosphorylation of thiamin monophosphate (TMP) to form thiamin
pyrophosphate (TPP), the active form of vitamin B 1.
- term:
id: GO:0009229
label: thiamine diphosphate biosynthetic process
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
IEA annotation for involvement in the thiamine diphosphate biosynthetic
process based on combined automated methods (UniRule, UniPathway UPA00060).
ThiL directly catalyzes the conversion of TMP to TPP (thiamine diphosphate),
which is the sole step of this sub-pathway.
action: ACCEPT
reason: >-
This is the most specific and accurate biological process annotation for ThiL.
The enzyme catalyzes the single step from TMP to TPP, which is precisely the
thiamine diphosphate biosynthetic process. UniPathway UPA00060 step UER00142
confirms this is a one-step pathway.
supported_by:
- reference_id: PMID:30867460
supporting_text: >-
Thiamine monophosphate kinase (ThiL) catalyzes the last step of thiamine
pyrophosphate (TPP) synthesis, the ATP-dependent phosphorylation of
thiamine monophosphate (TMP) to thiamine pyrophosphate.
- reference_id: PMID:18311927
supporting_text: >-
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent
phosphorylation of thiamin monophosphate (TMP) to form thiamin
pyrophosphate (TPP), the active form of vitamin B 1.
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: >-
NEW annotation. ThiL is a soluble cytoplasmic enzyme with no transmembrane
domains or signal peptides. The protein lacks any predicted export signals
and the PurM-like bilobal fold is characteristic of soluble cytoplasmic
enzymes. The BioReason SFT analysis also inferred cytoplasmic localization
based on domain architecture.
action: NEW
reason: >-
ThiL is a soluble enzyme that acts on cytoplasmic substrates (ATP and TMP).
The protein has no transmembrane domains, signal peptides, or other
localization signals. Cytoplasmic localization is consistent with its
enzymatic role in the thiamine biosynthetic pathway, where substrates and
products are cytoplasmic metabolites. Although no direct experimental
localization data exists for this archaeal protein, the inference is strong
based on protein architecture and pathway context.
supported_by:
- reference_id: file:METJA/thiL/thiL-deep-research-bioreason-sft.md
supporting_text: >-
the architecture lacks transmembrane segments or export signals and
matches a soluble PurM-like bilobal enzyme, the most plausible cellular
location is the cytosol
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO
terms
findings:
- statement: >-
InterPro2GO mapping from IPR006283 (Thiamine-monophosphate kinase-like)
to GO:0009228 (thiamine biosynthetic process). This is a correct but
relatively broad annotation.
- id: GO_REF:0000104
title: Electronic Gene Ontology annotations created by transferring manual GO annotations
between related proteins based on shared sequence features
findings:
- statement: >-
UniRule HAMAP MF_02128 transfers ATP binding and magnesium ion binding
annotations from characterized ThiL proteins. These are core mechanistic
features supported by crystal structures.
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings:
- statement: >-
Combined evidence from InterPro, RHEA, EC number, UniRule, and UniPathway
supports thiamine-phosphate kinase activity and thiamine diphosphate
biosynthetic process annotations.
- id: PMID:8688087
title: Complete genome sequence of the methanogenic archaeon, Methanococcus jannaschii.
findings:
- statement: >-
MJ0028 (thiL) was identified as part of the complete M. jannaschii genome
sequence. Only 38% of predicted proteins could be assigned a putative
function with high confidence.
supporting_text: >-
A total of 1738 predicted protein-coding genes were identified; however,
only a minority of these (38 percent) could be assigned a putative
cellular role with high confidence.
- id: PMID:18311927
title: Structural studies of thiamin monophosphate kinase in complex with substrates
and products.
findings:
- statement: >-
Crystal structures of A. aeolicus ThiL with AMP-PCP/TMP (substrates) and
ADP/TPP (products) established the direct in-line phosphoryl transfer
mechanism, distinguishing ThiL from other PurM superfamily members that
use phosphorylated enzyme intermediates.
supporting_text: >-
The results suggest that AaThiL utilizes a direct, inline transfer of the
gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme
intermediate.
- id: PMID:30867460
title: Crystal structures of thiamine monophosphate kinase from Acinetobacter
baumannii in complex with substrates and products.
findings:
- statement: >-
High-resolution structures of A. baumannii ThiL confirm the in-line attack
mechanism and reveal plasticity in active-site metal identity, though
magnesium is preferred for the transferred phosphate groups.
supporting_text: >-
The structures further support a previously proposed in-line attack reaction
mechanism and show a distinct variability of metal content of the active
site.
- statement: >-
ThiL is essential for A. baumannii growth and is a potential antimicrobial
target.
supporting_text: >-
the ATP-dependent phosphorylation of thiamine
monophosphate (TMP) to thiamine pyrophosphate
full_text_unavailable: true
- id: PMID:6284709
title: thiK and thiL loci of Escherichia coli.
findings:
- statement: >-
Original identification and naming of the thiL gene in E. coli, encoding
thiamine monophosphate kinase activity. Mutants lacking ThiL respond only
to thiamine pyrophosphate, not thiamine monophosphate.
supporting_text: >-
the latter lacks thiamine monophosphate kinase activity
- id: PMID:28115546
title: ThiN as a versatile domain of transcriptional repressors and catalytic
enzymes of thiamine biosynthesis.
findings:
- statement: >-
Archaeal thiamine biosynthesis is regulated by a transcriptional repressor
ThiR (not a riboswitch), and uses a chimeric pathway with eukaryote-like
Thi4 and bacterium-like ThiC components.
supporting_text: >-
thiamine biosynthesis in archaea is regulated by a transcriptional repressor,
ThiR, and not by a riboswitch
- id: PMID:26928142
title: From suicide enzyme to catalyst -- the iron-dependent sulfide transfer in
Methanococcus jannaschii thiamin thiazole biosynthesis.
findings:
- statement: >-
The M. jannaschii Thi4 ortholog uses exogenous sulfide and is catalytic
(multiple turnover), unlike the yeast Thi4p which is a suicide enzyme.
This establishes the upstream thiazole synthesis pathway feeding into ThiL.
supporting_text: >-
the Thi4 ortholog from Methanococcus jannaschii uses exogenous sulfide and
is catalytic
- id: PMID:12376536
title: "Comparative genomics of thiamin biosynthesis in procaryotes. New genes and regulatory mechanisms."
findings:
- statement: >-
Comparative genomics analysis reveals that archaea, eubacteria, and
eukaryota have different pathways for HMP and thiazole biosynthesis, but
the terminal ThiL step (TMP to TPP) is broadly conserved.
supporting_text: >-
eubacteria, archaea, and eukaryota have different pathways for the HMP
and hydroxyethylthiazole biosynthesis
core_functions:
- description: >-
ThiL catalyzes the ATP-dependent phosphorylation of thiamine monophosphate (TMP)
to form thiamine pyrophosphate (TPP), the active cofactor form of vitamin B1.
This is the terminal step of the thiamine diphosphate biosynthetic pathway.
The enzyme functions as a homodimer with a bilobal PurM-like fold, using a
direct in-line phosphoryl transfer mechanism with multiple magnesium ions
in the active site.
molecular_function:
id: GO:0009030
label: thiamine-phosphate kinase activity
directly_involved_in:
- id: GO:0009229
label: thiamine diphosphate biosynthetic process
locations:
- id: GO:0005737
label: cytoplasm
substrates:
- id: CHEBI:58937
label: thiamine(1+) monophosphate
- id: CHEBI:30616
label: ATP
supported_by:
- reference_id: PMID:18311927
supporting_text: >-
Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent
phosphorylation of thiamin monophosphate (TMP) to form thiamin
pyrophosphate (TPP), the active form of vitamin B 1.
- reference_id: PMID:30867460
supporting_text: >-
Thiamine monophosphate kinase (ThiL) catalyzes the last step of thiamine
pyrophosphate (TPP) synthesis, the ATP-dependent phosphorylation of
thiamine monophosphate (TMP) to thiamine pyrophosphate.
suggested_questions:
- question: >-
Has ThiL from M. jannaschii been directly assayed for thiamine-phosphate kinase
activity, and does the hyperthermophilic enzyme show any unusual kinetic or
stability properties compared to mesophilic homologs?
- question: >-
What is the physiological source of TMP in M. jannaschii -- does it use the
canonical ThiE (thiamine phosphate synthase) or the bifunctional ThiDN?
suggested_experiments:
- description: >-
Express and purify recombinant M. jannaschii ThiL (Q60337) and perform in vitro
kinase assays at thermophilic temperatures (65-85 C) to confirm thiamine-phosphate
kinase activity and determine kinetic parameters. Compare with mesophilic ThiL
enzymes to assess thermoadaptation.
hypothesis: >-
M. jannaschii ThiL will show optimal activity at hyperthermophilic temperatures
(around 80 C) with kinetic parameters comparable to characterized ThiL enzymes
from mesophilic organisms.
- description: >-
Determine the crystal structure of M. jannaschii ThiL to compare the active
site architecture with the known structures from A. aeolicus and A. baumannii,
particularly examining metal coordination geometry at the higher physiological
temperature of this organism.
hypothesis: >-
The M. jannaschii ThiL structure will reveal conserved active-site geometry with
potential thermostabilizing features (e.g., additional salt bridges, compact
hydrophobic core) compared to mesophilic homologs.